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Ectosymbiotic bacteria at the origin of magnetoreception in a marine protist.

ABSTRACT: Mutualistic symbioses are often a source of evolutionary innovation and drivers of biological diversification¹. Widely distributed in the microbial world, particularly in anoxic settings^2,3, they often rely on metabolic exchanges and syntrophy^2,4. Here, we report a mutualistic symbiosis observed in marine anoxic sediments between excavate protists (Symbiontida, Euglenozoa)⁵ and ectosymbiotic Deltaproteobacteria biomineralizing ferrimagnetic nanoparticles. Light and electron microscopy observations as well as genomic data support a multi-layered mutualism based on collective magnetotactic motility with division of labour and interspecies hydrogen-transfer-based syntrophy⁶. The guided motility of the consortia along the geomagnetic field is allowed by the magnetic moment of the non-motile ectosymbiotic bacteria combined with the protist motor activity, which is a unique example of eukaryotic magnetoreception⁷ acquired by symbiosis. The nearly complete deltaproteobacterial genome assembled from a single consortium contains a full magnetosome gene set⁸, but shows signs of reduction, with the probable loss of flagellar genes. Based on the metabolic gene content, the ectosymbiotic bacteria are anaerobic sulfate-reducing chemolithoautotrophs that likely reduce sulfate with hydrogen produced by hydrogenosome-like organelles⁶ underlying the plasma membrane of the protist. In addition to being necessary hydrogen sinks, ectosymbionts may provide organics to the protist by diffusion and predation, as shown by magnetosome-containing digestive vacuoles. Phylogenetic analyses of 16S and 18S ribosomal RNA genes from magnetotactic consortia in marine sediments across the Northern and Southern hemispheres indicate a host-ectosymbiont specificity and co-evolution. This suggests a historical acquisition of magnetoreception by a euglenozoan ancestor from Deltaproteobacteria followed by subsequent diversification. It also supports the cosmopolitan nature of this type of symbiosis in marine anoxic sediments.

SUBMITTER: Monteil CL

PROVIDER: S-EPMC6697534 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Ectosymbiotic bacteria at the origin of magnetoreception in a marine protist.

Monteil Caroline L CL Vallenet David D Menguy Nicolas N Benzerara Karim K Barbe Valérie V Fouteau Stéphanie S Cruaud Corinne C Floriani Magali M Viollier Eric E Adryanczyk Géraldine G Leonhardt Nathalie N Faivre Damien D Pignol David D López-García Purificación P Weld Richard J RJ Lefevre Christopher T CT

Nature microbiology 20190429 7

Mutualistic symbioses are often a source of evolutionary innovation and drivers of biological diversification1. Widely distributed in the microbial world, particularly in anoxic settings2,3, they often rely on metabolic exchanges and syntrophy2,4. Here, we report a mutualistic symbiosis observed in marine anoxic sediments between excavate protists (Symbiontida, Euglenozoa)5 and ectosymbiotic Deltaproteobacteria biomineralizing ferrimagnetic nanoparticl ...[more]

PMID: 31036911

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Ectosymbiotic bacteria at the origin of magnetoreception in a marine protist.

Publications

Ectosymbiotic bacteria at the origin of magnetoreception in a marine protist.

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